Embodiments of the invention relate to approaches for allowing an optical packet to be optically provided to a packet optical network, e.g. for allowing an optical communication between two or more packet optical networks enabling an optical bypass between two or more packet optical networks, for example packet optical mobile communication networks.
FIGS. 1A through 1C show examples for optical networks communicating with each other. FIG. 1A is a general representation of two packet optical networks exchanging signals/messages. FIG. 1B is a more detailed representation of the networks being a mobile core network and a mobile metro/access network. FIG. 1C is an even more detailed representation of possible implementations of the mobile networks from FIG. 1B.
As is shown in FIG. 1A, a first packet optical network 100 and a second packet optical network 102 are shown schematically. Within each of the networks 100, 102 local traffic occurs, as is represented by the arrows 104 and 106, which is only within the respective network 100 and 102. In addition, it may be desired to exchange information between the networks 100 and 102 which is referred to as cross traffic 108. The networks 100 and 102 are optical networks and the local traffic 104, 106 is done on the basis of optical signals. When communicating between the networks 100 and 102, the cross traffic 108 needs to transfer signals or messages among the two networks 100 and 102.
FIG. 1B shows an example for the configuration shown in FIG. 1A in which the network 100 is a mobile core network of a mobile communication system, including a plurality of nodes, for example a packet data network gateway 110 (P-GW), a service gateway 112 (S-GW) and a mobile management entity 114 (MME), which are shown only schematically as respective nodes in the mobile core network 100. The second packet optical network 102, in FIG. 1B is a mobile metro/access network 102 including a plurality of mobile access areas represented schematically by base stations 116a to 116c. Each of the access areas serves a plurality of mobile users, and the base stations communicate with each other on the basis of the X2 protocol, thereby generating the X2 traffic 106. The mobile metro/access network 102 and the mobile core network 100 need to communicate with each other, for example there needs to be a communication among the respective base stations 116a to 116c of the mobile metro/access network 102 with the serving gateway 112 (see S1 traffic 108).
FIG. 1C shows a further detailed representation of FIG. 1B, especially more details regarding the mobile core network 100 and the mobile metro/access network 102. The mobile core network 100 may include an HOPR mesh (HOPR=Hybrid Optoelectronic Router), and the mobile metro/access network 102 may include a plurality of POADM rings (POADM=Packet Optical Add/Drop Multiplex). The network 100 comprises the nodes 110 to 114 described with regard to FIG. 1B, each node including the resources 110a, 112a, 114a necessitated, for example CPUs, memory elements, and the like. Further, each of the nodes includes an optoelectronic router 110b, 112b and 114b for exchanging optical signals among the respective nodes and for converting the optical signals into electric signals for handling by the respective resources. The network 100 in FIG. 1C shows additional optoelectronic routers 118 and 120 for providing alternative connections between nodes 110, 112 and between nodes 112 and 114 or for providing additional access points for the network 100.
The mobile metro/access network 102 comprises several POADM rings, e.g., 122a to 122c. The first POADM ring includes three base stations 124a to 124c communicating among each other, thereby generating local traffic 106a, for example using the X2 protocol. The local traffic 106a is based on optical signals. The POADM ring 122b includes four base stations 126a to 126d communicating with each other in accordance with the X2 protocol, thereby generating local traffic 106b. Likewise, POADM ring 122c includes four base stations 128a to 128d communicating with each other in accordance with the X2 protocol, thereby generating the local traffic 106c. Communication among the base stations in the rings 122b and 122c, like in ring 122a, is based on optical signals exchanged among the respective base stations. Within each ring, one of the base stations, e.g. base stations 124a, 126a and 128a, is defined as the hub node for interfacing with the mobile core network for coupling the respective rings to the core network entities. The base station 124a of the first ring 122a is connected to the service gateway node 112, as is the first base station 126a of the second ring 122b. Via this interface, cross traffic 108a and 108b between the service gateway 112 and the first ring 122a and the second ring 122b, respectively, occurs. The third ring 122c is coupled via the further access node 118 of the core network 100 to the respective gateways described and respective cross traffic 108c is generated between the mobile core network and the third ring 122c. The cross traffic 108a to 108c may include S1 traffic.
In the above described optical networks 100, 102, optical routers/switches are used which are advantageous due to the low energy consumption and high capacity when compared to electrical routers/switches. FIG. 2 shows a comparison of the energy consumption at electrical switches/routers and optical switches/routers. As can be seen, the routers and Ethernet switches (see the upper two rows of FIG. 2) have the highest energy consumption which constantly drops when implementing the switches with optical components obtaining the lowest energy consumption when using an all optical switch (OOO switch: Optical-Optical-Optical switch). With the growth of data traffic in networks, for example the increase of mobile data traffic due to the rapid spread of smart phones and the commercialization of LTE services, there is a need to change the network transport technology from electrical packet switching to optical packet switching also between the core network and the metro/access network. Because of the different requirements in the different parts of an overall network different optical switching techniques may be used within the respective networks (for example the above core network 100 and the metro/access network 102). These networks may have different requirements regarding costs, network resilience, data rate, data aggregation, etc., different optical switching techniques may be used within the respective networks.
Thus, while there is already a solution for optical communication within the respective networks, there is currently no solution to efficiently interconnect different packet optical networks. Rather, at present the interconnection of different packet optical networks is done electrically, i.e. the above described cross traffic 108, 108a to 108c is done electrically. The cross traffic between the different packet optical networks is converted into the electrical domain, is electrically processed, for example in the IP/Ethernet layer, is electrically stored, for example in the electric buffer and is then converted back into the optical domain such that it can be understood by the target packet optical network. This OEO conversion (OEO=Optical-Electrical-Optical) and electrical processing necessitates a lot of time and leads to a high energy consumption. Further, such interconnection points also form a bottleneck with regard to the traffic transport between the different packet optical networks.
A similar problem occurs when considering only a single optical network which needs to receive external data packets which can be generated by the external packet provider in the optical domain. In such a situation, like above, it is necessitated to provide for the conversion of the external optical data packet into the electrical domain, to electrically process it and to convert it back into the optical domain of the network which needs to receive the external data packet, which again leads to the above mentioned problems regarding the OEO conversion and the electrical processing.